One of the major difficulties with previous studies of prostate cancer has been the lack of sufficient quantities of tissue from patients in whom there was accurate clinical information and accurate clinical followup. The other problem was a lack of sufficient patients in any one category, so that conclusions could be drawn. It is the job of the Clinical Core to overcome these problems. It will do this by providing material from patients who are extensively studied and followed in sufficient quantities to allow the proposed studies to be carried out. In order to ensure the accuracy and usefulness of the clinical and pathological data to be collected, specific forms have been developed. Serum PSA studies have become important in the management of patients with prostate cancer. Preliminary work with Dianon Systems, Inc. suggests that urinary levels of PSA may have a similar role. In order to further evaluate this, we will use urine from the patients enrolled in the Program Project. Every effort will be made to access tissue from minority patients. One major way that this will be accomplished is through Dr. Aaron Jackson's participation. Dr. Jackson will send the group in excess of 100 prostate cancer specimens a year, 95% of which will come from African-Americans.